Communication technology is the cornerstone of the modern information society. Among them, optical communication technology, with its advantages of high bandwidth, low loss, and anti-interference, is gradually becoming the core transmission method of future information. However, optical communication systems still have security risks, such as signal eavesdropping, data tampering, and channel interference. To address these challenges, an optical communication encryption technology based on CPolSK modulation is proposed. The results show that this technology has a 16% higher anti-side-channel attack performance than traditional modulation at a lower signal-to-noise ratio, and in the free-space optical communication (FSO) scenario, the decoding accuracy of encrypted image information transmitted through optical communication exceeds 95%.
Communication technology is the cornerstone of the modern information society. Among them, optical communication technology, with its advantages of high bandwidth, low loss, and anti-interference, is gradually becoming the core transmission method of future information. However, optical communication systems still have security risks, such as signal eavesdropping, data tampering, and channel interference. To address these challenges, an optical communication encryption technology based on CPolSK modulation is proposed. The results show that this technology has a 16% higher anti-side-channel attack performance than traditional modulation at a lower signal-to-noise ratio, and in the free-space optical communication (FSO) scenario, the decoding accuracy of encrypted image information transmitted through optical communication exceeds 95%.
Free-space optical (FSO) communication provides a promising alternative solution to the traditional radio frequency (RF) communications. Compared to the RF technology, there are many advantages of FSO communications, such as ultra-high bandwidth, license-free spectrum, low inter-channel interference, and energy-efficient transmission. The potential applications for FSO communication include the last-one-mile access link from the fiber-based backbone network, low earth orbit (LEO) satellite communications, high-altitude base station platforms or vehicles, deep-space communications, and in-building automation connections. As the FSO technology becomes mature and increasingly involved, the security and reliability requirements of such applications also become crucial. Regarding the security issues, although the FSO communication is inherently more secure than the RF counterpart due to high directivity of its line-of-sight (LOS) link, it can still suffer from optical wire-tapping attack. There are many different application schemes that an eavesdropper can still probe the FSO link. Traditionally, to protect the communication, many works have been done on encryption layer and upper network layer, such as computationally intensive cryptographic algorithms and message exchanging protocols. In recent years, physical-layer security (PLS) has been getting more attentions as it provides an extra layer of security against eavesdropping. The PLS schemes, in general can be categorized into two main categories: classical PLS and quantum key distribution (QKD) protocols. The classical PLS is based on the information theoretic security analysis, while the QKD security is guaranteed by the quantum mechanics laws. Both techniques have been studied for FSO channels. In the first half of this dissertation, we study the PLS in a LOS FSO channel using orbital angular momentum (OAM) multiplexing and show that higher secrecy capacity can be achieved using OAM multiplexing technology in the presence of atmospheric turbulence effects. Then, we proposed an adaptation scheme for QKD system over FSO channel with different QKD protocols, i.e. BB84 and decoy state protocols. By adapting the source brightness based on the channel condition, we optimized the secret key rate (SKR) of the QKD system. Furthermore, we proposed a multiple spatial modes-based QKD system with backpropagation method to increase the total SKR through parallel channels. Regarding the reliability of an optical communication system as well as information reconciliation for both PLS and QKD schemes, the forward error correction (FEC) becomes an essential technique to enable high-speed transmission. The FEC with low-density parity-check (LDPC) codes has been studied for decades from LDPC block codes to the most recent spatially-coupled (SC) LDPC codes. For FSO communications, due to the time-varying nature of FSO channels, the capability of rate adaptation is important to achieve a consistent reliable transmission. In the second half of this dissertation, we proposed unified FPGA-based architecture to implement both quasi-cyclic (QC) LDPC codes and SC-LDPC codes with rate adaptation capability. The performance is verified through FPGA emulation to show good error floor properties. To further validate the rate adaptation capability, we have built a spatial light modulator (SLM)-based FSO channel emulator to test the adaptive coding scheme. Furthermore, we have conducted a fiber-based experiment with our rate adaptative coding scheme to show that the proposed adaptive coding scheme can be also used in dynamic fiber-based networks.
The development of communication technology is currently progressing at an extremely rapid pace. One of the most widely applied technologies for data transmission is fiber optic communication, which uses light as the transmission medium. This technology enables data to be transmitted at very high speeds. However, in the process of data transmission, a security mechanism is required to protect information from unauthorized access. Attacks on fiber optic networks can lead to significant alterations in the data received compared to the data sent by the transmitter. This poses a serious risk, particularly when the transmitted data is confidential. Two methods that can be employed to secure fiber optic networks are Optical Steganography and Optical Encryption. The working principle of Optical Steganography involves hiding signals in public channels, while Optical Encryption functions by encrypting the transmitted signals. Both methods can be implemented using OptiSystem software. According to the results of this study, Optical Encryption demonstrates a higher level of reliability compared to Optical Steganography. Optical Encryption achieved a Q-Factor value of 14.65 and a BER of 6.55×10−49. In terms of Q-Factor, Optical Encryption is shown to be 16.3% more effective than Optical Steganography and 90.4% more efficient compared to designs without a security system.
The Free Space Optical Communication (FSOC) technology has gained widespread popularity due to its multitude of advantages. FSOC offers enhanced security due to its narrow beam, Line-of-Sight (LoS) nature, and resistance to Electromagnetic Interference (EMI). However, ensuring data confidentiality in case of interception is critical. This work demonstrates data encryption using the Advanced Encryption Standard-128 (AES-128) to secure FSOC links. An encrypted optical signal was transmitted over a 2 km link and successfully decrypted at the receiver, ensuring that intercepted data remains unintelligible without the decryption key. This approach enhances FSOC’s reliability for secure transmission of sensitive or confidential information.
Abstract Optical encryption techniques in over the last 10 years have become more important in the area of optical information processing. Several applications, including online payments, medical or biometric image storage or transmission, private military applications, police identification techniques, online banking platforms, governmental services, identity (ID) cards, etc., are only a few examples. Require special and reliable security in the transmission and storage of images. Since digital picture information may be readily accessed by hackers via transmission over the Internet or other communication channels, the issue of photos with unlawful usage is becoming more and more severe. A more effective and secure means of communicating images may be offered via optical encryption. The encryption mechanism and keys are needed at the receiver side in order to decrypt the original optical data. Picture security becomes a highly important subject in communication science as a result of network growth and rising need for image transmission. There are several security issues with picture data, including forgery detection and illegal access. The most straightforward method of picture protection is to encrypt it as text. The traditional text encryption algorithms are inappropriate for picture encryption because of the high correlation present in image data. Over the last two decades, a number of optical approaches have been proposed for photo encryption, with the specific advantage of processing two-dimensional (2D) image data in parallel conduction mode. Therefore, we are doing an extensive investigation on optical image encryption in this work.
The growing awareness of the vulnerability of information transmitted on communication systems within the government, military and commercial sectors, has stimulated a number of areas of research within the optical community to design optical hardware encryption systems providing inherent immunity to espionage techniques. This paper describes a hardware optical encryption technique that utilises off the shelf telecommunication equipment and negates the necessity for an independent key distribution system with respect to the data transmission system, as is common with alternative encryption system implementations. This method also lends itself easily to fiber optic or free space communication and is applicable within any optical waveband. The encryption-decryption of the optical signal is achieved through low coherence optical interferometry. This requires the instantaneous processing and analysis of the signal, optically, to retrieve the relevant optical phase information hidden in the transmitted optical noise. This technology allows an authorised user to transmit encrypted information at a high data rate securely, while maintaining opaqueness to an unauthorised observer that data transmission is occurring. As the instantaneous optical field properties of the signals present in the system are essential to the optical encryption - decryption process, the system is inherently protected against electronic recording and advances in computational decryption algorithms. For organisations wishing to protect sensitive data and levels of communication activity these are highly desirable features.
Fiber Optics Communication is also one of the major branch which is widely used in current communication world. Due to several advantages of fiber optics communication over different conventional wired communication method it is having higher priority. Though fiber optic transmits large amount of data quickly over long distance, it is vulnerable to various security attacks. The fiber optic cable can be easily tapped. Fundamental improvements can be achieved for the entire network by increasing the optical network’s performance in terms of channel capacity, data rate, and processing speed. Furthermore, the security of the optical network has an impact on the security of the entire communication system. Optical network security can be effectively protected by fiber-based methods, including all optical signal processing, optical key distribution, optical steganography, and optical chaos-based communication. Fiber-based devices do not radiate an electromagnetic signature and are immune to electromagnetic interference. To provide end to end secure fiber optic communication, a special encryption algorithm based on Advanced Encryption Standard (AES) is employed. The proposed encryption algorithm is simulated and the performance is analyzed. In this paper we are mostly dealing with the basics of fiber optics working principle, priority over other conventional communication system and role of fiber optics communication in computer networking and its vulnerabilities.